Convertible Preferred Stock and Stockholders Equity - Summary of Common Stock Reserved for Future Issuance (Detail) - shares	Sep. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Common stock reserved for future issuance	7,612	4,787
Warrants to Purchase Common Stock
Class of Stock [Line Items]
Common stock reserved for future issuance	380	466
Public Warrants to Purchase Common Stock
Class of Stock [Line Items]
Common stock reserved for future issuance	3,734	3,734
Stock Options
Class of Stock [Line Items]
Common stock reserved for future issuance	1,423	444
RSUs
Class of Stock [Line Items]
Common stock reserved for future issuance	583
Authorized for Future Equity Grants
Class of Stock [Line Items]
Common stock reserved for future issuance	1,092	143
Authorized for Future ESPP Purchases
Class of Stock [Line Items]
Common stock reserved for future issuance	400